1. Field of the Invention
The present invention relates to a thin-film magnetic head used to record information on and reproduce information from a magnetic recording medium such as a magnetic disk.
2. Description of Related Art
As shown in FIG. 4, a conventional thin-film magnetic head mounted on a magnetic disk drive apparatus has a slider 10 serving as the main body of the head, and a pair of air bearing rails 11A and 11B projecting from the front side (i.e., the lower side, as viewed in the figure) of the slider 10 and extending longitudinally thereof. The air bearing rails 11A and 11B face a magnetic recording medium (not shown), such as a magnetic disk. Air inlet portions 12A and 12B for floating the magnetic head are formed at one end of each of the air bearing rails 11A and 11B, respectively, while air outlet portions 13A and 13B are formed at the respective other ends. Thin-film electromagnetic transducers 14A and 14B are provided at the same end of the slider 10 as the air outlet portions 13A and 13B. Leading terminals are extended from the electromagnetic transducers 14A and 14B, and are connected with a plurality of wire connecting portions, more specifically, bonding pads 21A, 21B, 22A, 22B, 23A and 23B, which are formed on the same plane. The electromagnetic transducers 14A and 14B, and the bonding pads 21A, 21B, 22A, 22B, 23A and 23B are all provided on the same side surface of the slider 10, and these members are arranged in a pattern which is symmetrical with respect to the central axis of the side surface, and which is repeated vertically.
As shown in FIG. 5, the thin-film electromagnetic transducer 14A on the side of the air bearing rail 11A includes a recording and reproducing coil 16A formed as a film coiled with an insulator layer 15A between the turns, leading terminals 17A, 18A, and 19A extended from the recording and reproducing coil 16A, and a film-shaped magnetic core 20A. The recording and reproducing coil 16A has a sandwich structure at the position of the film-shaped magnetic core 20A, in which the core 20A is sandwiched from above and below. A recording and reproducing gap (not shown) is formed at the tip of the magnetic core 20A, that is, on the relevant surface of the air bearing rail 11A.
The thin-film electromagnetic transducer 14A having the above-described construction provides the following function. When electrical connection is established between, for instance, the leading terminals 17A and 19A, a magnetic field is generated from the tip of the magnetic core 20, and the magnetic field generated is used to record information on the magnetic recording medium. Information is reproduced by causing the magnetic field generated by the magnetic recording medium to be picked up by the magnetic core 20, then detected by the coil 16A. The electromagnetic transducer 14B on the side of the other air bearing rail 11B has the same construction and function. Although the magnetic head has the two electromagnetic transducers 14A and 14B, recording or reproducing is generally performed by using only one of the transducers 72.
As shown in FIG. 6, wires 30 are bonded, by means of an ultrasonic wire bonder or the like, to the bonding pads 21B, 22B and 23B by solder portions 31 so that these pads 21B to 23B are connected with an electrical circuit of the magnetic disk drive. The slider 10 is supported by gimbals 50; more specifically, the surface of the slider 10 which is opposite to that surface of the slider facing the magnetic recording medium is secured to the gimbals 50 by a resin or the like. The wires 30 have one of their respective ends bonded by the solder portions 31 to the corresponding bonding pads 21B to 23B, with the respective other ends being connected with the electrical circuit of the magnetic disk drive. In order to allow this wiring, the wires 30 are passed through a tube 40 for preventing damage to the wires 30, the tube 40 being fixed to the gimbals 50 by caulking, etc.
Recently, however, the conventional thin-film magnetic head has been found to entail the following problems.
(1) The advent of small and portable personal computers which incorporate magnetic disk drive apparatuses and which are of the so-called laptop or handheld type has led to the demands for small and portable magnetic disks which are capable of high-density recording.
In these circumstances, it has also been demanded that magnetic heads used in magnetic disk drive apparatuses be thin-film magnetic heads which are small, light, and usable in high-density recording, rather than the metal-in-gap, bulk type to which a greater part of the currently available magnetic heads belongs. The size of magnetic disks has been gradually decreasing from 3.5 inches to 2.5 inches, then to 2 inches since the advent of laptop or handheld computers. However, to reduce the size of the conventional thin-film magnetic head has been difficult since three pairs of the bonding pads 21A and 21B, 22A and 22B, and 23A and 23B are provided on the side surface of the slider 10, while being arranged in a vertically repeated pattern. If one dares to reduce the size of the magnetic head, the pattern in which the bonding pads of the conventional magnetic head are arranged results in the problem that the bonding pads are arranged too close to each other, thereby involving the risk of short-circuiting between two adjacent pad structures during the connection of leads, etc. If the bonding pads themselves are made small, there is a risk of failure in electrical insulation.
(2) During the fabrication of, for instance, the electromagnetic transducer 14A, a protective film of alumina or the like is formed by puttering on the surface of the leading terminals 17A, 18A and 19A. Therefore, when the bonding pads are to be formed, it is necessary to remove the protective film material (alumina) on that portion of the side surface corresponding to the bonding pads. The removal of the material (alumina), which is performed by an abrading method or the like, involves not only an increase in the man-hour required but also a risk of deteriorating the quality of product.
(3) The wires 30 are extended in such a manner that, while they are connected with the bonding pads 21A, 22A and 23A on the side surface of the slider 10, they are passed through the tube 40 fixed to the gimbals 50 on the surface of the slider 10 which is opposite to the magnetic recording medium facing the surface of the slider 10. Thus, the wires 30 are extended over two surfaces of the slider 10. This means that due considerations must be given so as not to cause slack, etc. In addition, it is not possible to adopt a bonding method, such as a ball bonding method or a bump solder bonding method, which is commonly, used in the wiring of ICs, thereby making it difficult to improve the efficiency of the soldering operation.
U.S. Pat No. 4,317,149 issued to Elser et al. discloses a magnetic head structure similar to that of the prior art related to the present invention as described above.